Jack-screw



(No Model.) l v N. D. RUSSELL. JAKSCRBW.

No. 459,769. y Patented Sept. 22, 1891.

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NATHANIEL D. RUSSELL, OF LACONIA, NET HAMPSHIRE.

JACK-SCREW.

SPECIFICATION forming part of Letters Patent No. 459,769, datedSeptember 22, 1891.

Application led March 17, 1891.

T0 all whom it may concern.-

Be it known that I, NATHANIEL D. RUS- SELL, a citizen of the UnitedStates, residing at Laconia, in the county of Belknap and State of NewHampshire, have invented a new and useful Jack-Screw, of which thefollowing is a specification.

This invention relates to the jack-screws generally used in raisingheavy weights; and the object of the same is to effect certainimprovements thereon.

To this end the invention consists ofl the specific details ofconstruction hereinafter more fully described and claimed, and asillustrated in the sheet of drawings, wherein- Figure l is a sideelevation of this improved jack partly uuscrewed. Fig. 2 is a centralvertical section of the same, the upper member being partly inelevation. Fig. 3 is an enlarged vertical section through the center ofthe head of the upper member. Fig. e is a horizontal section through thehead of the lower member.

Referring to the said drawings, the letter B designates a suitable base,into whose upper end is screwed the lower screw member L, which istubular. Into this member is screwed the center screw member C, which isalso tubular, and into the latter member is screwed the upper screwmember U, which is solid, and a washer IV is swivcled by a pin P to thecenter of the head of the upper member, the edges of the washer beingraised so as to take the superimposed weight off the head of the pin andpermit the head of the member to turn beneath the washer, as isobviously necessary in the operation of the device.

I have shown in the drawings a jack comprising three screw members; butI desire it to be understood that I may employ but two or any numbergreater than one. The threads are here shown as of different pitch; butthe pitch maybe the same, if preferred. Each of the screw members iscomposed of a threaded shank, as shown, and an enlarged head havingholes for the reception of a bar or handle H, by means of which themember may be turned. The holes or openings O through the head of theupper member U passes diametrically through the same, preferably atright angles to each other, as shown in Fig.

semi No. 385,424. on mobiel.)

3 and as will be clearly understood; but in those members where thethreaded shank of the member above screws through the head it will beobviously impossible to pass the handle completely through the head,even if the openings O were so made. Hence in those screw members otherthan the upper member I arrange the openings O in parallel chords, asshown in Fig. 4, and the handle H may be inserted in an obvious manner.

The letters S designate set-screws, which are seated in the heads of thescrew members and base, as best seen in Fig. 4, and areadapted to bescrewed home, so as to impinge uponl the threaded shank of the memberwithin and to prevent the turning thereof in either direction.

In operation the jack is brought into position with the washer IV underthe load to be lifted. If it be desired to lift the load slowly for ashort distance and by the exercise of comparatively little force, thehandle is inserted in one of the openings O and the upper member Uturned in the proper direction. To lift the load more rapidly and withthe exercise of less power, lower screw members might be turned byinserting the handle I-I in the openings O', as will be obvious. Ineither case all the set-screws S are tightened, except the one below thehead in which the handle is inserted. It very frequently occurs,however, that the load is to be lifted for a considerable distance, andthis can be accomplished by my improved jack in the following manner:The lower screw member is first unscrewed, so as to raise the load fornearly the length of this member and the set-screw in the head of thebase tightened to hold the member in elevated position. The neXt memberis then unscrewed in a similar manner and the setscrew in the head ofthe lower member tightened, and so on up to the uppermost member, whichmay be held elevated by the set-screw in the head of the member nextbelow. If it were not for the set-screws, the members could notbe-turned independently. Hence I consider their use highly desirable.

The herein-described lifting-jack, the same comprising a base, a numberof screw meinbers screwing into each other and the lowermost one intothe base, each member having IOO an enlarged head, the head of theuppermost In testimony that I claim the foregoing as member having'diametri@ openings and the my own I have hereto athxed my signature 111heads of the other members having openings presence ot' two Witnesses.

on the chords thereof7 and set-screws through NATIIANIEL D. RUSSELL. 5the head of the base and the heads of all the Wvtnesses:

members but the uppermost, as and for the S, S. JEWET'F,

purpose hereinhefore sei; forth. l IV. A. PLUmfIER.

